1. Field of the Invention
The present invention generally relates to laser pen pointers, and more particularly to an accessory device for modulating the laser beam output of a pen-clip actuatable laser pointer in accordance with an electrical input signal.
2. Brief Description of the State of the Art
Since the beginnings of time, man has always been fascinated with light. From the discovery of fire to the development of the light bulb, man has found new ways of using light to improve the general quality of life on Earth.
In recent times, the technological innovation of the visible laser diode has made it is much easier to produce visible laser beams for use in various applications. In response to the need for low power visible laser beams, a wide variety of VLD pen-based pointers have been recently developed. In general, each laser pen pointer includes a pen-like housing within which a solid-state visible laser diode, batteries and a laser drive circuit are compactly mounted. Many commercially available VLD pen pointers also have a pen clip for fastening onto a shirt pocket, like conventional pocket pens.
The ML211 Laser Pointer 1 sold by Metrologic Instruments, Inc. is illustrated in FIGS. 1 and 1A. As shown in FIG. 1A, the VLD 2 and laser drive circuit 3 are realized on a printed circuit (PC) board 4, which is arranged along with batteries 5 in a pen-like housing 6. As shown, pen-like housing 6 has conductive battery containing section 6A and a top section 6B which are electrically isolated from each other by way of insulative support collar 9. As shown, the positive (+) terminal of the battery supply is electrically connected to the barrel section 6A, whereas the negative (-) terminal of the battery supply establishes direct contact with the negative supply element 7 mounted to laser drive circuit 3 on PC board 4. In turn, the negative supply element 7 is directly connected to VLD drive circuit 3, and indirectly connected to electrically conductive pen-clip 8, which is fixedly mounted to the barrel section of the pen-like housing of the laser pointer. In order to electrically isolate the PC board from the metallic barrel section 6A, the PC board is supported within electrically insulative support collar 9. Also, VLD 2 is disposed along the optical axis 10 of a lens system 11 and an aperture stop 12 disposed at the end of the top section of the laser pointer.
In order to activate the VLD of the laser pointer shown in FIGS. 1 and 1A, the user simply depresses pen-clip 8 against the outer conductive surface 13 of the barrel section 6A, so that the conductive tip portion of the pen-clip contacts the conductive barrel section, thereby causing electrical power to flow from the batteries to the laser drive circuit. In turn, the laser drive circuit energizes the VLD to cause a narrowly focused visible laser beam to project from the aperture stop 12 at the end of the laser pointer.
The ML211 Laser Pointer from Metrologic Instruments, Inc. is exemplary of state of the art in VLD pen pointing devices. The uses to which such solid-state laser pointing devices can be put are limited only by the imagination of its user. A variety of conceived uses for pen-based laser pointers are described in the Instruction Booklet provided with each ML211 Laser Pointer, namely: Pointing at a Projected Image on a Screen; Making the Laser Beam Visible; Viewing Imperfections in an Ice Cube; Using Color Filters to Absorb Laser Light; Reflecting a Laser Beam with Colored Opaque Objects; Scanning Bar Codes; Reflection and Refraction at a Water Surface; Observing Internal Reflectance in a Test Tube; Observing Internal Reflections in a Curved Water Jet; Viewing Frosted Light Bulb Filaments; Proving the Law of Reflection; Deflecting the Laser Beam with Voice or Music; Curving a Laser Beam; Bending a Laser Beam with A Razor Blade; Spreading a Laser Beam with a Narrow Slit; Making a Laser Beam Twinkle; and Exercising Your Dog or Cat.
While the use of laser beams in optical communication applications is well known, unfortunately, however, there is no simple means for modulating the intensity of the laser beam produced from pen-actuatable laser pointers, such as the Metrologic.RTM. ML211 Laser Pointer. Consequently, such pen-based laser pointers are not readily usable for optical communication demonstration or laser beam modulation experiments.
Thus, there is a great need in the art for an accessory device that can be used in conjunction with pen-clip actuatable laser pointers in order to modulate the intensity of the laser beam produced therefrom, in response to either the instantaneous amplitude, frequency, or phase characteristics of an electrical input signal, such as an audio or video signal.